Josiah Bartlet has a lot to answer for. That American president existed only as a creation of television fiction and yet he has had more influence on thinking and writing about our politics than many real-life British politicians.

The last season of The West Wing, the feel-good series about a liberal American president and his improbably attractive, dynamic and idealistic staff, was screened some time ago. Yet it seems to play on an endless loop in the heads of the Westminster classes and those who report on them.

When Tony Blair was in Number 10, some of his staff liked to fantasise that they were acting out a British version of The West Wing. They even put the show's stirring title theme on their answering machines. Mr Blair did not do that, but he did entertain ambitions to turn Downing Street into a discount version of the White House.

After visits to the Oval Office, he used to half-jokingly complain to his aides that they ought to call him "Mr Prime Minister" in emulation of the way that George Bush's staff addressed him as "Mr President".

Mr Blair had a notion to merge Number 10 with the cabinet office in the hope that would create a simulacrum of the West Wing. He was thwarted by resistance from the senior civil service, his own lack of determination when it came to reforming Whitehall, and the power of his rival for the presidency, one Gordon Brown.

Now it is the Tories who dream of replacing Downing Street as Pennsylvania Avenue. Several headlines have talked of "David Cameron's West Wing". When I recently visited the corridor of offices occupied by the Tory leader and his senior team, they looked exactly as they had the week before: an unglamorous suite of rooms with clubland furniture, situated in an undistinguished office block on the edges of the parliamentary estate many hundreds of miles from the Potomac. On that occasion, members of the shadow cabinet and their staff were rushing around in a lather induced by one of the expenses scandals.

When the political editor of the Spectator visited the same corridor, he found himself transported across the Atlantic: "To visit Norman Shaw South is to see a political machine whirring beautifully," writes Fraser Nelson in the most recent edition of the magazine. "It is like a British version of The West Wing: the key players walking in and out of their rooms and having 45-second impromptu meetings in the corridor."

In similar vein, a report in Friday's Independent talks about "a cast of advisers, tacticians, policy wonks and spin doctors that would not look out of place walking the corridors of President Bartlet's West Wing".

On the same day, the Guardian predicted that "a West Wing would be created in Downing Street" when Mr Cameron moves in.

What the Spectator, the Independent and the Guardian accurately reflect is the Cameroons' ambitions for themselves. These accounts draw on research by Conservative Intelligence, a new group set up by Tim Montgomerie, founder of ConservativeHome. His report is essential reading for anyone who wants to understand the power grid in the Cameron Tory party. It even comes with a handy wall chart that is entitled - this you may have guessed - "David Cameron's West Wing".

Several things leap out from this deeply researched guide to the inner wiring of the Tory high command. One theme is that formal job titles, experience and being elected matter much less in the Tory hierarchy than proximity to and intimacy with the leader.

Mr Cameron has surrounded himself with a cabal whom he has known for decades, having first met them at school, university or as junior desk officers at Conservative party HQ.

Ed Llewellyn, his chief of staff, went to Eton, just like the Tory leader, and to Oxford, just like the Tory leader. Their friendship became firm when they worked together at the Conservative research department. Kate Fall, the deputy chief of staff, is another Oxford graduate who took a degree in PPE - just like the Tory leader. The chief executive of the Conservative party, Andrew Feldman, has been a close friend of the leader since they were at Oxford together. David Cameron and Steve Hilton, the guru of his leadership campaign four years ago, first met each other in the Conservative research department in the 1990s. Mr Hilton has recently returned from California, preparatory to joining his friend in a pivotal role inside the Oval Office - sorry, Downing Street.

This is not novel. Whether they are American or British, most leaders have an inner cabal. Winston Churchill had his cronies. Harold Wilson had his "kitchen cabinet". The difference was that the influence of the leader's gang was balanced by the real cabinet.

That does not look like being the case in a Cameron government. Another striking feature of the power dynamics at the top of the Conservative party is how few of its MPs have any meaningful influence over policy or strategy. Members of the shadow cabinet are privately quite frank about how little their voices count. Their meetings are generally good-natured, but they know the real decisions are not taken there. They come to get their orders, not to have a debate.

The most significant exception is George Osborne, who has a huge amount of say over policy and a tight grip over the Tory machine. Mr Osborne is not just the shadow chancellor. He is also his party's general election co-ordinator. Moreover, he often gives the impression that he regards the latter role as the more important. Mr Osborne raised some eyebrows at a recent private meeting in the City when he was heard to remark that "40% of my time is spent on economics" - meaning that most of his hours are spent on campaigns and tactics. Mr Osborne seemed to think that 40% was an impressively large amount of his time to find to spend on economics; some of his audience thought it was a worryingly low proportion for the man who expects to be chancellor in less than a year's time.

The Cameron-Osborne duo, with one doing the presentation and the other running the machine, has obvious echoes of the Blair-Brown diarchy. The Tory team think they have learnt one lesson: they do not want Cameron-Osborne to be a sequel to the perpetual feuding between Number 10 and the Treasury when it was Blair-Brown. They rightly note that Tony Blair and Gordon Brown squandered a lot of their energy wrestling each other for control of the steering wheel of government and came dangerously close to careening it over the edge of the cliff on several occasions.

The toxin in that relationship was Gordon Brown's failure to get over the fact that he was not prime minister. Mr Cameron and Mr Osborne are lucky in that there is no Granita-style deal to poison their relationship. That has made their partnership much easier and more friendly so far. They seem to understand that it will be substantially harder to sustain good relations when they face the pressures of power. It is being suggested that they will try to replicate their cosy arrangement in opposition by creating a joint office in Downing Street.

Yet they are kidding themselves if they think that will stop them having big arguments. It is in the nature of the jobs that prime ministers, who are prone to worry over opinion polls, see the world differently from their chancellors, who are more inclined to fret about the finances.

The very fact that they are so close now is likely to make the disputes more emotionally intense when they get into the inevitable conflicts about tax, spending and all the other points of friction that ignite sparks between Numbers 10 and 11. Because a Conservative government will have to cut spending savagely, some of those arguments are going to be epic.

In his description of "David Cameron's West Wing", Tim Montgomerie describes the leader's gang as "a small group of politically motivated people who have organised ruthlessly and rather brilliantly to turn around the fortunes of one of Britain's major parties". He observes: "The biggest decisions are drafted in very small groups."

He could have written all that - in fact, some of us did write all that - about another small group of politically motivated people who ruthlessly and rather brilliantly turned around the fortunes of a major British party. It exactly describes the creation of New Labour, including the making of the biggest decisions in tiny circles.

That is the one bit of The West Wing that Tony Blair did manage to recreate in Downing Street. There were a lot of "45-second impromptu meetings in the corridor". More often, the informal, unminuted, haphazard gatherings of the prime minister and his inner circle happened on the sofa in his den. The practice of making big decisions in tiny groups has continued, with a different cast list, under Gordon Brown.

Many of the most disastrous episodes of their premierships - the Ecclestone affair, the dossier on Iraq, the outing of Dr David Kelly, the Election That Never Was, the YouTube expenses fiasco - were a result of decisions made in a rush by ad hoc clusters of the inner gang. David Cameron might usefully take note. Small groups of people dashing down corridors and taking decisions in less than a minute makes for compelling television drama. As a way of running a government, it is over-rated.